title: Reduced FHIT expression is associated with mismatch repair deficient and high CpG island methylator phenotype colorectal cancer.
abstract: Colorectal cancer (CRC) is a heterogeneous disease and a major contributor to world cancer mortality rates. Molecular subtypes of CRC have become standards for CRC classification and have established prognostic potential. Here, we attempt to corroborate and provide further insight pertinent to the fragile histidine triad (FHIT) gene in microsatellite instable (MSI), microsatellite stable (MSS), and CpG island methylator phenotype (CIMP) CRC subtypes. We employed array comparative genomic hybridization and multiplex ligation-dependent probe amplification (MLPA) techniques to survey genomic aberrations in FHIT gene and their effects on FHIT protein expression using immunohistochemistry (IHC) in a CRC cohort. We further studied FHIT protein expression by IHC in a larger CRC cohort defined for its mismatch repair (MMR) protein expression and genomic methylation profiles. Our results show FHIT genomic deletions centered in exons 4 and 5 in most of MSI-CRC samples. Moreover, we confirmed the significant association of FHIT protein expression diminution (p=0.035) with MSI-CRC. In the larger cohort, reduced FHIT protein expression was significantly associated with CIMP-high subtype of CRC (p=0.009) and loss of PMS2 protein expression (p=0.017). We conclude that FHIT expression may be a valuable marker for CRC subtyping, and its diagnostic, prognostic, and therapeutic potential should be perused.
authors.affiliation: Human Genetics Unit, Pathology Department, Faculty of Medicine, Health Sciences Center, Kuwait University, State of Kuwait.
authors.forename: Rabeah Abbas
authors.initials: RA
authors.lastname: Al-Temaimi
authors.forename: Sindhu
authors.initials: S
authors.lastname: Jacob
authors.forename: Waleed
authors.initials: W
authors.lastname: Al-Ali
authors.forename: Diana Ann
authors.initials: DA
authors.lastname: Thomas
authors.forename: Fahd
authors.initials: F
authors.lastname: Al-Mulla
mesh_terms: D017766:Acid Anhydride Hydrolases / Q000032:analysis / Q000235:genetics*; D015331:Cohort Studies; D003106:Colon / Q000378:metabolism / Q000473:pathology*; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000473:pathology*; D018899:CpG Islands; D019175:DNA Methylation; D053843:DNA Mismatch Repair; D015536:Down-Regulation; D005260:Female; D017353:Gene Deletion; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008297:Male; D053842:Microsatellite Instability; D009363:Neoplasm Proteins / Q000032:analysis / Q000235:genetics*; D012007:Rectum / Q000378:metabolism / Q000473:pathology*; D000099170:Bis(5'-adenosyl)triphosphatase
chemical_list: D017766:Acid Anhydride Hydrolases; D009363:Neoplasm Proteins; D000099170:Bis(5'-adenosyl)triphosphatase
keywords: CpG island methylator phenotype; aCGH; colorectal cancer; fragile histidine triad gene; microsatellite instability